BOSTON -- At a time the Red Sox could ill afford to lose a reliever, the team suspended closer Alfredo Aceves for "conduct detrimental to the team."

The announcement was made almost two hours into Boston's 10-9 loss to the Kansas City Royals that went 12 innings, the second extra-inning game in three nights for the Sox. The suspension began immediately, meaning Aceves will miss the last two games (Sunday and Monday) of the Royals' series.

General manager Ben Cherington, who earlier on Saturday had put the finishing touches on the biggest trade in team history, said he had no comment on the Aceves matter. Manager Bobby Valentine was only slightly more forthcoming, refusing to offer details of what had transpired the night before when Aceves -- apparently upset at being passed over for a save opportunity Friday night -- stormed into Valentine's office. According to a source, Aceves demanded a meeting with Cherington, but was told that was not possible at the moment because Cherington was in the midst of trade negotiations with the Dodgers.

Aceves slammed the office door loudly upon his departure.

Valentine had championed the pitcher since the beginning of spring training, when he first auditioned for a starter's role and was then made closer after Andrew Bailey went down with a thumb injury that required surgery. Bailey, who subsequently strained his right forearm, missed the season's first 116 games before being reinstated Aug. 14.

"I'm a little disappointed," Valentine said, while refusing to characterize what transpired with Aceves, other than to suggest it might have had something to do with his not getting the call in the ninth.

"You've just got to know the difference between right and wrong. That's all we ask."

The manager said the decision to suspend Aceves was made "last night, maybe this morning." Asked if Aceves's suspension could affect his role on the team, Valentine replied: "We're taking it day by day."

Aceves last pitched Thursday night in a 14-13, 10-inning loss to the Angels, in which he was charged with a yield of six hits and five runs in just an inning-plus, giving up home runs to Vernon Wells and Kendry Morales. He was charged with a blown save and the loss, continuing a dreadful August in which he is 0-2 with a 10.24 ERA in nine appearances, giving up 11 hits and 9 runs in 9 2/3 innings. In that span, he has given up four home runs, matching the number of home runs he allowed in the season's first four months.

Friday night, with the Sox ahead 4-3, Bailey entered with two outs in the eighth inning and then was sent out for the ninth to record his first save in a Red Sox uniform. According to NESN broadcaster Jerry Remy, Aceves tore off his uniform jersey as he made his way from the bullpen to the clubhouse, then went into Valentine's office.

Aceves was not in the clubhouse when reporters were allowed entry after the game. His agent, Tom O'Connell, said he wanted time to review the situation before he made a comment.

Valentine had noted before the game that his bullpen was "stressed," even with the team adding Junichi Tazawa, who had just been optioned back to Pawtucket the night before, onto the roster.

Valentine had used seven relievers, who threw 7 1/3 innings, in Thursday's extra-inning loss. Three relievers worked two innings Friday night, before Valentine went through seven more relievers Saturday to pitch the final six innings.

Bailey and Vicente Padilla were each used for a third straight game. Andrew Miller pitched in back-to-back games, while Tazawa was used for the third time in four games.

"I used all the guys I didn't want to use," Valentine said.

Valentine said the club was considering adding a fresh reliever for Sunday's game.

Information from ESPNBoston.com contributor Tony Lee was used in this report.